Efficiency and cost-effectiveness of copper electrowinning is, and for a long time has been, important to the competitiveness of the copper industry. Research and development efforts in this area have thus focused, at least in part, on mechanisms for decreasing the total cost for anodes used in copper electrowinning, which directly impact the cost-effectiveness of the electrowinning process.
One type of anode employed in an electrowinning operation typically comprises a lead or a lead alloy, such as, for example, Pb—Sn—Ca. One significant disadvantage of using such anodes is lead contamination of the copper cathodes. Specifically, during the electrowinning operation, small amounts of lead are released from the surface of the anode and ultimately cause the generation of undesirable sediments, sludges, particulates suspended in the electrolyte, other corrosion products, or other physical degradation products in the electrochemical cell and contamination of the copper product. Another disadvantage of using lead anodes in conventional electrowinning processes is the need to add cobalt sulfate to the copper electrolyte to help stabilize lead-based anodes for at least one of control of surface corrosion characteristics of the anode, control of formation of lead oxide, and/or prevention of deleterious effects of manganese in the system. Improvements are needed in the materials used for anodes useful for electrochemical reactions, as well as in the construction of the anodes.